Now and then I come across this notion of the angry atheist. The atheist with axes to grind, who only disbelieves because X happened to them. The underlying theme is that only negative personal experiences could drive one away from gods. You had a bad father or you were ostracized or your parents divorced - on and on. I see these ideas and I see lots of atheists leap in to suggest they never had these problems and I think "good for you".
But I sure as fuck did. And if I am to be honest, they HAD to inform my nonbelief. The fact that I accepted my atheism two decades after some life changing negative events occured suggests that my disbelief was not a direct result of the negative experiences, BUT (and this is tricky to talk about because it will leave one open to the types of accusations many theists are wont to make) the fact that I was detribed, defathered and and decultured at a young age played a huge part in my decision, I believe. I was not afraid of losing the relationships theism provides, for example. I was not afraid of seeming arrogant, or disrespectful. I have learned what actually matters and how to maintain it. I have learned how to move into a social group and make alliances based on nothing more than my ability to communicate and empathise. I can live on little, sleep wherever I need to and, if it really has to happen, defend myself physically.
I write all that to get to this question: do my ideas track with the universe as it presents itself? When you ask me to take a notion seriously, what can you show me to persuade me it also tracks? Theism has only a few things to offer, such as popularity, tradition and community. I am not against these things, but none of them are reasons to hold a belief about the cosmos. They are simply socializing mechanisms. Not bad or good, but also not facts.
(TLDR) So, how much of a stereotypical atheist do you feel like you are? Are you mad at your dad, angry at evangelicals, snotty and stuck up - and do you suppose any of these atttributes argue for the existence of a god? Because, in the end, that is the only question that matters to an atheist.
As to treatment, I am very happy (!) to report I am on the other side of that. I have learned techniques and was able to ween myself from the drugs, as a matter of fact. of course I still have it, and it still tends to overwhelm me for small periods of time, but now I see it for what it is and I know how to move through it. Yes, it certainly is science - or rather the recognition of the physical properties of the condition and the application of science to gain some control and perspective. Science is a method, and controlling depression involves the methods of science directly. One of the most important things I took away from my therapies was this simple truth. If you have a broken arm, you use the science of medicine to allow your body to repair it quickly and effectively. If you have depression, same deal. It's not a character flaw or a weakness of will. It's a medical condition and with the right help if can be dealt with effectively.
Further, when I do get an episode now, it is almost...interesting to observe it. That is one of my techniques. I feel the "trough" and analyze the effects as though I were studying it in a laboratory - and this actually robs it of its emotional power. The pain is real enough, but I know it passes, and the tendency to give in to old habits in response is replaced by the curiosity of experiencing the mind changing states - outside of my own illusion of will. Each episode teaches me something about my self and about the universe, andI think it helps me grow as a person.
I actually did a survey using a slightly modified version of Rotter's original LoC in college and found no statistical difference between self purported atheists and other religious groups apart from Catholics (avg was around 0.6 with about 0.1 std. dev.) Note that the sample size (N=450) of each group (n=[30-200]) was too small to draw definite conclusions. I was attempting to research potential different marketing strategies for risky assets for atheists vs religious people in an I/O psych class. If I recall correctly, the only group which tend to repeatably have an internal LoC are members of the armed services.
The LoC is best utilized as a tool to understand the individual religion's, and it's group of adherents, predisposition for foundational impression of predetermination ("fate") on the individual, and less to do with the actual individual's subsequent actions based on these taught predispositions. In plain English, LoC is a bad tool for measuring individuals.